As cocaine use becomes more prevalent among young women, the effects of using cocaine during pregnancy and the effects on the child's environment of cocaine use become increasingly important concerns. Research to date has presented conflicting results on the effects of prenatal cocaine exposure on the newborn and very little research has followed the exposed offspring past the early months of age. In order to study the range of effects associated with prenatal cocaine exposure, a longitudinal study is required. This proposal represents a unique opportunity to follow a large prospective cohort and to begin to understand the effects of prenatal cocaine exposure. In an ongoing study, we are assessing cocaine use during each trimester of pregnancy and infant outcome at birth and 12 months postpartum. This is a proposal to assess the cohort at 24 months of age. Dramatic changes occur between 12 and 24 months in the infant's development, notably increased sophistication in language, problem-solving and motor skills. At 24 months postpartum, we will assess infant physical, developmental, behavioral and neurophysiological characteristics. The effect of prenatal cocaine exposure will be analyzed by trimester of pregnancy. Careful assessment of covariates such as sociodemographic characteristics, maternal psychiatric symptom levels, and current drug use and environmental characteristics will allow us to evaluate the relationship between prenatal cocaine use and child outcome while controlling for these factors. Preliminary analyses of the first 115 deliveries in the ongoing sample demonstrate differences between the offspring of the women who use cocaine prenatally and those who are not exposed. Infants of frequent users are more likely to be low birth weight and small-for-gestational age. Data from the EEG-sleep studies indicate that infants exposed to cocaine prenatally have different EEG patterns compared to infants not exposed to cocaine and compared to infants exposed to alcohol or marijuana. Women who use cocaine during pregnancy are also more likely to report a higher rate of previous pregnancy losses.